The present invention relates to recessed light fixtures and in particular to such a fixture employing a dichroic lamp (e.g., MR11, MR16, and cool beam par lamps) which reflects light forwardly while permitting heat to pass rearwardly therethrough.
A predominate light source within the lighting industry is the low voltage MR16 dichroic lamp. That compact light source provides crisp white light with pin point control in a two-inch lamp diameter. This lamp is available as a cool beam lamp, the glass structure being coated with a dichroic reflective coating. That coating allows about 60% of the radiant heat to transmit rearwardly through the reflector surface, while reflecting nearly 99% of the visible light forwardly. However, the additional heat emitted towards the rear of the lamp results in various manufacturing concerns, such as:
1) Increased skin temperatures of the recessed housing. Underwriters Laboratories (UL) sets limits on skin temperatures disposed in direct contact with insulation.
2) The emission of visible light rearwardly along with the heat from the dichroic reflector. That allows end users to see into the recessed housing and is aesthetically unacceptable.
3) Increased heat in the recessed housing. This can shorten the life of components such as magnetic or electronic transformers, or discolor painted surfaces.
4) Increased heat around the socket. That can increase the lamp pin/socket contact temperatures above the lamp manufacturer's design levels, causing short lamp life and necessitating the use of more expensive wire and socket components.
It is known from Kim U.S. Pat. No. 3,769,503 and David U.S. Pat. No. 5,130,913 to provide a heat-reflective surface behind a dichroic lamp to reflect the heat forwardly. In particular, each of those patents discloses the provision of a metallic cup-shaped heat reflector spaced behind a dichroic lamp which acts on heat radiation that has passed rearwardly through the reflector surface of the lamp to reflect that radiation forwardly.
In the Kim fixture, the heat reflector is pivotally supported on an axle to rotate about the dichroic lamp. In the David fixture, the heat reflector is supported by the lamp or by the socket in which the lamp is coupled, but there is no disclosure of how the lamp and socket themselves would be supported.
When employing a heat reflector in combination with a dichroic lamp, there are serious concerns involving the mounting of the components which are not addressed by either of the Kim and David patents. That is, it is necessary to achieve a proper orientation of the lamp to ensure that the light is directed as intended, and also to prevent the glass lamp from contacting the hot reflector. This must be achieved while maintaining a proper alignment between the metallic heat reflector and the lamp to ensure that the heat is reflected by the metallic element in an optimum direction with respect to the lamp. This means that a reliable amount of positional control must be exerted upon both the lamp and the heat reflector. However, such control should not result in excessive pressure being applied to the lamp, which could cause damage to the lamp.
Furthermore, MR16 lamps are supposed to have a UL listed lens installed in the front thereof to protect the user in the rare case the hologen lamp capsule explodes (non-passive failure). In a typical MR16 installation, a gimbal ring holds the lens, and the lamp sits in the gimbal ring such that the front rim of the lamp abuts the lens. Such an arrangement not only obstructs the light radiation, but also obstructs the escape of heat from within the lamp, whereby an undesirable heat build-up can occur.
Also, in the typical installation, it is possible for the lamp to be installed without the lens, thereby violating UL requirements.